These are the only replica fossils I have and are all scale. The rest are real. And out of these the only one I painted was the old Ward's T-rex skeleton in the center. I got it free from the Ward's booth at GSA 2008 after years of people and little kids scratching it up and breaking parts off in their display area.
First thing I would recommend is determining what formation/location your fossil replica is likely from.
I went with the classic Big Bend brown colors for my rex as I'm a Texan after all. An example for yours would be: Is it a Velociraptor from the Gobi or a Deinonychus from Lake Texhoma or a Utah Raptor from the Isle of Skye etc.?
Pictures online of historic finds will give you your specific colors. They can vary from light brown and blood red in the oxidized areas to pink and mint green in the semi-reduced Morrison Formation. You'd be surprised at how many of the classic Jurassic critters are green when you look at the real bones.
As for technique it depends on the type of fossil. You want a pretty shiny smooth texture for a claw. I would use a fine textured wash with enough future to break up the water tension for a smooth finish over a slightly lighter base shade. A great product for this is the combination Polyurethane stain and sealer mix (Minwax Polyshades as a brand example) that folks use as a quickshade for miniature painting. Then use a light black wash on top of that to really bring out the details (one made from ink will go on smoother and keep from making everything too dark to make out the shading from your first colored wash.
Keep in mind that fossils are often mottled in color if they have been permineralized (most vertebrate bone) so the washes are the best way to simulate that effect IMHO.
And for finish I would go with flat on the bone joint and satin on the claw itself.
Now that I think about it since it's such a small project you probably would be better off to go grab a couple pre-mixed washes for $2 apiece at your local Hobby Lobby/tabletop game store.
Mini Example using Badab Black and Pecan Satin Minwax to make a rustbucket spaceship.
